John dahlstrom



(No Model.)

J. DA-HLSTRUM. VALVE GEAR FOR STEAM ENGINES.

Patented Jan. 2, 1894.

invilzvl' IIIIIIIII IL Nr'rsn dramas Fares? @rmcie.

JOHN DAHLSTRUM, OF BUFFALO, NEW YORK, ASSIGNOR OF ONF-FOURTII TO HARRYll. BARCLAY, OF SAME PLACE.

VALVE-=GEAR FOR STEAM ENGlNES.

SPECIFICATION forming part of Letters Patent No. 51 1,836, dated January2, 1894.

Application filed June 13,1893. Serial No 477,418. (No model.)

To all whom it may concern.-

Be it known that 1, JOHN DAnLs'rRon, a citizen of the United States,residing at Buffalo, in the county of Erie and State of New York, haveinvented new and useful Improvements in Valve-Gear for Steam-Engines, ofwhich the following is a specification.

This invention relates to direct acting steam engines which are providedwith a main 1o slide valve and an auxiliary slide valve connected withthe main valve, such, for instance, as are used in steam pumps.

Qne object of my invention is to improve the construction of the valvemechanism by contriving it in such a manner that the auxiliary valve isactuated wholly by mechanical means, while the main valve is operated,during part of its stroke, by the auxiliary valve, and during theremainder of its stroke by steam pressure.

Another object of my invention is to improve the mechanical meanswhereby the auxiliary valve is operated.

In the accompanying drawings:-Figure 1 is a longitudinal sectionalelevation of a direct-acting steam engine provided with my improvementsand showing the piston at the end of its backward stroke and the mainvalve in its central position. Fig. 2 is a longitudinal section of thesteam chest and valves, showing the main valve at the end of its forwardstroke. Fig. 3 is a fragmentary longitudinal section of the steam chestand main valve, showing the latter in its foremost position, the sectionbeing taken on one side of the center for the purpose of showing theexhaust cavity in the main valve. Figs. 4

and 5 are vertical transverse sections in lines 4-4: and 5-5, Fig. 1,respectively. Fig. 6 is a bottom plan view of the main valve.

Like letters of reference refer to like parts in the several figures.

A represents the steam cylinder, B the piston and b the piston rod.

4 5 0 represents the cylindrical steam chest which is arranged parallelwith the steam cylinder.

cl 07, represent the main frontand rear steam ports leading fromopposite ends of the steam chest to opposite ends of the steamcylinders.

E is the exhaust chamber arranged on the under side of the steam chestand opening centrally into the under side thereof.

e 6 represent the main front and rear exhaust ports arranged between themain steam 5 5 ports and the exhaust chamber and extending from thesteam chest to the steam cylinder.

F represents a hollow main slide valve which reciprocates in the steamchest, and which is composed of two pistons ff connected by a contractedneck f forming a main exhaust cavityf between said pistons.

G represents the steam chamber arranged above the steam chest andprovided with main front and rear steam passages g g opening into theend portions of the steam chest, diametrically opposite the steam ports01 d.

H represents the steam supply pipe connected with the steam chamber.

During the reciprocating movement of the main slide valve its exhaustcavity alternately connects the main front and rear exhaust ports withthe exhaust chamber, and one of its pistons closes the main steampassage and port in one end of the steam chest thereby shutting offsteam to the adjacent end of the steam cylinder, while the other pistonopens the main steam passage and port in the other end of the steamchest, thereby admitting 8o steam to the opposite end of the steamcylinder, as shown in Fig. 2.

I represents an auxiliary slide valve, preferably of cylindrical form,arranged to reciprocate in the bore of the main slide valve. The mainand auxiliary slide valves are ca pable of lengthwise movement upon eachother, but this movement is limited by a transverse bolt 2' secured tothe main slide valve and passing through a longitudinal slot 1; in theauxiliary slide valve. The auxiliary slide valve is actuated Wholly bymechanical means, while the main slide valve is actuated partly bymechanical means and partly by steam pressure.

jj' represent auxiliary front and rear steam ports which extend from thesteam chamber into the steam chest on theinner sides of the steampassages g g, and It k are auxiliary front and rear steam passagesformed in the upper portion of the main slide valve and extending fromthe periphery to the bore thereof. When the main slide valve is in itscentral position in the steam chest, as shown in Fig. 1, its pistonsclose the main steam passages and ports at both ends of the steamchamber and chest, and both its auxiliary steam passages 70 7a are inline with the auxiliary steam ports 3' j of the steam chamber. When themain slide valve is in this position and the auxiliary slide valve is ateither end of its movement, one of the auxiliary steam passages in themain slide valve is closed and shuts oif steam to the adjacent end ofthe steam chest, while the other auxiliary steam passage is open andadmits steam to that end of the steam chest, which causes the main slidevalve to be shifted toward the opposite end of the steam chest, asrepresented in Fig. 2.

Z Z represent front and rear exhaust channels formed lengthwise in thebottom portion of the bore of the main slide valve and extendinginwardly from both ends of the latter.

m m represent auxiliary front and rear exhaust ports formed in the lowerportion of the main slide valve between the exhaust channels and themain exhaust cavity, and extending from the bore to the periphery of themain slide valve.

n n represent auxiliary front and rear exhaust cavities which are formedin the under side of the auxiliary slide valve and which alternatelyconnect the front exhaust channel with the front auxiliary exhaust port,and the rear exhaust channel with the rear auxil iary exhaust port.

923 represents the Valve rod, secured to the front end of the auxiliaryslide valve, and passing through the front head of the steam chest. Thefront end of this valve rod is guided on a standard N secured upon themain frame of the engine.

0 represents a transverse rock shaft which is journaled in bearings o 0formed on the standard N underneath the valve rod and which is actuatedby a depending rock arm P secured with its upper end to the rock shaftoutside of the bearing 0 and with its lower end to a cross head 19 onthe piston rod by a link p.

Q representsa rock finger which is mounted loosely with its lower end onthe rock shaft on the inner side of the bearing 0' and which engagesloosely with its upper end in an eye q formed on the Valve rod.

g g represent radial tappets formed on the rock finger on opposite sidesof its pivot.

R represents a collar secured to the rock shaft between the rock fingerand the bearing 0 and provided with radial tappets r r which arearranged on opposite sides of the rock shaft, and which are adapted toengage with the tappets of the rock finger for shifting the valve rodand the valves connected therewith. The tappets of the collar and rockfinger are so disposed that when the tappets on one side of the rockshaft are in contact with each other, the tappets on the opposite sideare separated by an intervening space. This space produces lost motionduring the first portion of the forward and backward strokes of thepiston rod and causes the valve rod to be actuated only during the lastportion of each stroke.

In the position of the parts represented in Fig. 1, the piston hascompleted its backward stroke and the main valve occupies its centralposition, thereby closing the main steam and exhaust ports and cuttingoff communication with both ends of the steam cylinder. In this positionof the parts the rear tappet r of the rock shaft bears against the reartappet g of the rock finger, and the auxiliary valve has been movedforwardly,.ther.eby

clearing the rear auxiliary steam passage of the main valve K andadmitting steam into the rear end of the steam chest. The steam nowenters the rear end of the steam chest and drives the main valveforwardly into the position shown in Fig. 2, thereby clearing the rearmain steam passage and port and admitting steam to the rear end of thesteam cylinder. This causes the main piston to move forwardly and thepiston rod of the same to carry the rock arm forward. At the same timethat the main valve clears the rear main steam passage and port itsexhaust cavity connects the front main exhaust port with the exhaustchamber, as most clearly shown in Fig. 3. During the first portion ofthe forward movement of the main valve, when it is actuated by steampressure, its front auxiliary exhaust port m opens into the front mainexhaust port e of the steam cylinder and the front auxiliary exhaustcavity 71 of the auxiliary valve connects the front auxiliary exhaustport m with the front exhaust channel Z of the main valve, whereby thesteam is permitted to exhaust from the front end of the steam chest intothe exhaust chamber. During the last portion of the forward movement ofthe main valve communication between the front exhaust channel I and thefront auxiliary exhaust cavity n is out off and the front auxiliarysteam passage K clears the auxiliary valve and connects the front mainsteam passage 9 with the front end of the steam chest as represented inFig. 2, thereby admitting steam into the front end of the steam chestwhereby the main valve is cushioned at the end of its forward stroke andjarring or pounding is prevented. During the last portion of the forwardmovement of the main piston the front tappetr of the rock shaft engageswith the front tappet q of the rock finger and moves the valve rod andthe mainand auxiliary valvesconnectedtherewith backwardly. During thebackward movement of the auxiliary valve the rear end of its slot bearsagainst the transverse bolt of the main valve and carries the latterwith it. At the end of the backward movement of the auxiliary valve thefront auxiliary steam passage K arrives opposite the front auxiliarysteam port j of the steam chamber, thereby admitting steam into thefront end of the steam chest, whereby the main valve is driven by steampressure to the end of its backward stroke. As the main valve clears thefront main steam passage and port during the last portion of itsbackward movement steam is admitted into the front end of the steamcylinder, which causes the main piston to be moved backwardly and themain and auxiliary valves to be shifted forwardly into the positionshown in Fig. 1. In this manner the auxiliary valve is positivelyoperated from the piston rod and the main valve is positively operatedfrom the auxiliary valve during the first part of its stroke and movedby steam pressure during the remainder of its stroke. This constructionof the valves and their operating mechanism, is comparatively simple, asthe valves have only a rectilinear and no oscillatory movement, andenables the valves to be produced at comparatively small cost and to beeasily fitted and kept in working order.

I claim as my invention- 1. The combination with the steam cylinder, thepiston, and the steam chest, ofa main slide valve arranged in said steamchest, an auxiliary valve arranged in the main slide valve, operatedfrom the piston, and having a limited reciprocating motion with the mainslide valve, whereby both valves are moved together until the movementof the auxiliary valve is arrested, when the stroke of the main Valve iscompleted by the action of the steam, substantially as set forth.

2. The combination with the steam cylinder, the piston and the steamchest, of a main valve arranged to slide in the steam chest andcontrolling the steam for actuating the piston, an auxiliary valvearranged to slide Within the main valve and provided with a slot, atransverse bolt or pin secured to the main valve and entering the slotof the auxiliary valve, the ends of said slot being arranged to come incontact with said pin or bolt during the first portion of the stroke ofthe auxiliary valve, and intermediate mechanism whereby the auxiliaryvalve is operated from the piston, substantially as set forth.

3. The combination with the steam cylinder, the piston and the steamchest connected with the cylinder by main steam and exhaust ports, ofthe steam chamber having main front and rear steam passages opening intothe end portions of the chest, an exhaust chamber, a hollow main valveprovided with a central exhaust cavity for connecting the exhaust portswith the exhaust chamber, and an auxiliary valve arranged to slide inthe main valve and operated from the piston, substantially as set forth.

4. The combination with the steam cy1inder, the piston, the steam chestconnected with the cylinder by main steam and exhaust ports, the steamchamber connected with the steam chest by main steam passages andauxiliary steam ports, and the exhaust chamber, of a hollow main valveprovided centrally with a main exhaust cavity and having auxiliary steampassages extending from its outer side to its bore, and adapted toregister with the auxiliary steam ports and the main steam passages ofthe steam chamber, and having longitudinal exhaust channels formed inits bore and auxiliary exhaust passages extending transversely from thebore to its outer side, and an auxiliary valve arranged to slide withinthe main valve and provided with auxiliary exhaust cavities adapted toconnect the auxiliary exhaust passages with the exhaust channels,substantially as set forth.

5. The combination with the steam cylinder, the piston, the steam chestand the steam chamber, of a main slide valve arranged in said steamchest, an auxiliary slide valve arranged in the main slide valve, andcapable of a limited longitudinal reciprocating motion with the mainslide valve, and a rock finger connected with the auxiliary valve andactuated from the piston, whereby both valves are moved together untilthe movement of the auxiliary valve is arrested, when the main valve ismoved farther and its stroke is completed by the action of the steam,substantially as set forth.

6. The combination with the steam cylinder, the piston, the piston rod,the steam chest, the valve and the valve rod, of a rock arm connectedwith the piston rod, and a rock finger connected with the valve rod andshifted by the rock arm during the last portion of the movement of thelatter, substantially as set forth.

7. The combination with the steam cylinder, the piston, the piston rod,the steam chest, the valve and the valve rod, of a rock shaft, a rockfinger mounted loosely on said shaft and connected with said valve rod,a rock arm secured to the rock shaft and connected with the piston rod,and tappets on the rock shaft adapted to engage with tappets on the rockfinger, said tappets being so disposed that the rock finger is actuatedduring the last portion of the forward or backward stroke of the piston,substantially as set forth.

lVitness my hand this 10th day of June, 1893.

JOHN DAHLSTROM.

Witnesses:

THEO. L. POPP, F. (J. GEYER.

